1. Field of the Invention
The present invention relates to a radio communication permission control system which carries out an access permission control when one of communication terminals such as portable phones accesses a reception apparatus such as a base station for communication start.
2. Description of the Related Art
A communication apparatus using a mobile communication terminal such as a portable phone becomes popular rapidly. Especially, attention is recently paid to the communication :apparatus of the CDMA (code division multiple access) communication system which is difficult to undergo influence of noise and interference from other signals by using the spectrum spreading technique. The mobile terminal such as a portable phone adopts a cell system to attempt the effective use of a frequency band, and a channel is allocated to the mobile terminal in each cell.
By the way, the number of channels possible to be allocated in one cell, that is, the number of communicable mobile terminals which can communicate and call at a time is finite. Therefore, as a typical example, the number of mobile terminals which request communication at a time in one cell exceeds the permissible number of communication terminals in some probability. In such a case, the phenomena will occur in which it is not possible to connect with a base station regardless of requests of communication.
FIGS. 1A and 1B show a random access channel (RACH) system for the channel acquisition and it is used in a part of the communication terminals of the CDMA communication system. In the system shown in these figures, a random access channel system is used for an upward link channel from the mobile terminal to the base station. The communication terminal (not shown) requesting the communication outputs a preamble signal 11 composed of a predetermined code sequence as shown in FIG. 1A at the time when trying to start communication. When receiving the preamble signal 11, the base station (not shown) replies an ACK (affirmative) signal 12 to the mobile terminal as shown in FIG. 1B, when permitting the communication. The base station replies a NACK (negative) signal when the base station does not permit the communication, although it is not illustrated. The mobile terminal receives the ACK signal 12 and start the communication and outputs a message section 13 having transmission data as the content as shown in FIG. 1A.
In this way, in the random access channel system, the preamble signal 11 is used as a signal requesting message section 13. In other words, the message section 13 itself is common to all the mobile terminals, and the signal used for each mobile terminal to request a use right of the message section 13 to the base station is the preamble signal 11.
The number of message sections 13 which the base station can allocate in one cell is finite. Therefore, as described above, a specific mobile terminal transmits the preamble signal 11 once again, if still requesting the communication when the specific mobile terminal has transmitted the preamble signals 11 but is not permitted to communicate for the reply of the NACK signal. In such a case, when the communication chances are equally allocated to the mobile terminals which have sent out the preamble signals 11, the specific mobile terminal is occasionally not given a chance each time. Such a specific mobile terminal must wait for the communication permission for a long time.
For this reason, a proposal is made to eliminate such inequality. For example, in Japanese Laid Open Patent Application (JP-A-2000-32530), a mobile station in a distant place is given an opportunity to transmit under the situation in which the mobile stations in the neighborhood of a base station continuously tries to transmit signals. In this proposal, the mobile terminal on the position where the electric wave is relatively weak can be protected. However, the communication opportunity cannot be given in a higher priority to the mobile terminal in which access is refused regardless of the near and far positions when the accesses compete.
Also, in another proposal, data for specifying the mobile terminal in which a communication request is refused is stored in the base station. When the mobile terminal transmits the preamble signal 11 in the next opportunity, the message section 13 is allocated in,a higher priority to the mobile terminal corresponding to the stored data under the situation where accesses from mobile terminals compete. To realize such a proposal, what data should be stored in the base station is important as the data for specifying the mobile terminal.
As the simplest technique, it will be considered that a unique preamble signal 11 is allocated to every mobile terminal and a code sequence of the preamble signal is stored in the base station as the data for specifying a mobile terminal. For this purpose, it is presupposition that different preamble signals 11 are allocated to the respective mobile terminals separately, as in the phone number. However, such a technique cannot be adopted for all mobile terminals in the communications system. For example, in the communications system which is planed to introduce in every country of the world since 2001, and is called W-CDMA (Wideband Code Division Multiple Access) system, a random access channel system is adopted in the same way. However, the number of kinds of the preamble signal 11 prepared in a same cell (area) is a ten and a few. Therefore, when the mobile terminals more than the number of kinds exist in the same area, the mobile terminal which has transmitted preamble signal 11 cannot be specified by this preamble signal 11.
In conjunction with the above description, an adaptive array receiving apparatuses disclosed in Japanese Laid Open Patent application (JP-A-Heisei 9-247005). In this reference of the adaptive array receiving apparatus, an adaptive control is turned off for a preamble section (t2) of a reception signal and turned on for a data section (t3). In order to obtain a sufficient converging time, the reception data are read out twice and the converging operation is carried out for the reading operation. The number of time of repetition of the reading operation is predetermined based on adopted data format length of the system. In this way, an adaptive signal processing section (7) extracts only a signal transmitted,:from a specific terminal from among reception signals when the reception signals compete.
Also, a directional control antenna apparatus is disclosed in Japanese Laid Open Patent application (JP-A-Heisei 10-70502). In this reference, the directionality control antenna apparatus has an array antenna which transmits and receives electric wave to a mobile station in its area for a base station. A frequency convert section converts a reception signal of the array antenna into an intermediate frequency signal or a baseband frequency signal and converts a transmission signal of the intermediate frequency signal or the baseband frequency into a transmission frequency signal. The incoming direction estimating section estimates the incoming direction of the electric wave from the mobile station using the output signal from the frequency converting section and estimates the number of stations existing in the area in the direction of the mobile station. The antenna directionality control unit changes the phase and amplitude of the transmission signal or the reception signal and turns the direction of the peak of the directional beam of the array antenna to the direction of the mobile station estimated by the incoming angle estimating section. The reception from the mobile station and the transmission to the mobile station are carried out in a time divisional manner by use of the same directional beams formed by the antenna directionality control unit.
Also, a directional control antenna apparatus is disclosed in Japanese Laid Open Patent application (JP-A-Heisei 11-215049). In this reference, a mobile station has a communication signal transmitting section which transmits a communication signal, and a control signal transmitting section which transmits a control signal in a relatively low rate the communication signal. The base station has an array device using an antenna which has a wide directional pattern. In the directional control antenna apparatus, one or more array antennas carry out transmission/reception with one or more mobile stations existing around the mobile station. The frequency converting section converts a reception signal from the array device into an intermediate frequency signal or a baseband frequency signal in case of the reception. In transmission, it converts the intermediate frequency signal or the baseband frequency signal for the transmission into a transmission frequency signal. The band-pass filter for the control signal passes through only a signal of the frequency band of the control signal from the output signal from the frequency converting section. The incoming direction estimating section estimates the number of stations and the direction where the mobile station exists from the output of the band-pass filter for the control signal. The antenna directionality control unit changes the phase and amplitude of the intermediate frequency signal or the baseband frequency signal of the reception and the transmission and forms a sharp directional beam of the array antenna such that the directional gain higher than the directional pattern of the array device is obtained. The antenna directionality control unit turns the directional beam direction of the peak to the direction of the mobile station estimated by the incoming direction estimating section. Thus, communication with the mobile station is carried out by the same directional beam set by the antenna directional control unit in the transmission and the reception.
Also, a direction determining method in a cellar mobile communication network is disclosed in Japanese Laid Open Patent Application (P2000-31896A). In this reference, a sequence of symbols including a known training sequence from antenna array is stored. Space processing is repetitively carried out to the stored sequence of symbols for generating the influence of the antenna array having main lobe in a plurality of different and continuous directions of a polar diagram. A correlation measuring reference is calculated between a composite signal and known training sequence for every direction to determine a correlation measuring reference. A ratio of the correlation measuring reference for every direction to power of the composite signal is calculated to determine a direction measuring reference. Using the direction measuring reference, the direction of the mobile terminal is determined.
Therefore, an object of the present invention is to provide a radio communication permission control system in which a mobile terminal can be specified and can start communication with a priority, if the mobile terminal transmits a communication start request once again when the communication start request has been transmitted but the request is not permitted.
In an aspect of the present invention, a radio communication permission control apparatus includes a request receiving section, a reply section, an estimating section, a storage section, a determining section and a priority section. The request receiving section receives communication start request signals from requesting communication terminals. The reply section replies to each of the requesting communication terminal based on priority levels of the requesting communication terminals, a response indicating whether or not to permit communication start every time the request receiving section receives each of the communication start request signals. The estimating section analyzes the communication start request signal and estimates a position relation with the requesting communication terminal to generate position relation data. The storage section stores the position relation data. The determining section determines whether or not the position relation data of each of the requesting communication terminals to which the communication start are not permitted as prohibited communication terminals falls within a range which is predetermined based on each of the position relation data stored in the storage section, and stores the position relation data in the storage section. The priority section increases the priority levels for the prohibited communication terminals.
The position relation data may indicate a direction of each of the requesting communication terminals from the radio communication permission control apparatus. In this case, the determining section may determine whether or not a direction of the requesting communication terminal indicated by the estimated position relation data is in a predetermined directional range corresponding to any of the position relation data stored in the storage section.
Also, the position relation data may indicate an incoming angle of the communication start request signal transmitted from each of the requesting communication terminals to the radio communication permission control apparatus. In this case, the determining section may determine whether or not an incoming angle of the communication start request signal from the requesting communication terminal indicated by the estimated position relation data is in a predetermined angle range corresponding to any of the position relation data stored in the storage section.
Also, each of the requesting communication terminals may transmit position data of the requesting communication terminal together with the communication start request signal. In this case the estimating section may extract the position data as the position relation data. Also, the position relation data may be the position data indicating a position of each of the requesting communication terminals. In this case, the determining section may determine whether or not a position of the requesting communication terminal falls within a predetermined position range corresponding to any of the position relation data stored in the storage section.
Also, the position relation data may be held in the storage section for a predetermined time period.
Also, the predetermined time period may be a time period during which the requesting communication terminal is regarded not to move farther than a predetermined distance.
In another aspect of the present invention, a method of permitting communication in a radio communication permission control apparatus is attained by (a) receiving communication start request signals from requesting communication terminals; by (b) replying to each of the requesting communication terminal based on priority levels of the requesting communication terminals, a response indicating whether or not to permit communication start every time the reception of each of the communication start request signals; by (c) analyzing the communication start request signal and estimating a position relation with the requesting communication terminal to generate position relation data; by (d) determining whether or not the position relation data of each of the requesting communication terminals to which the communication start are not permitted as prohibited communication terminals falls within a range which is predetermined based on each of the position relation data stored in the storage section, and stores the position relation data in a storage section; and by (e) increases the priority levels for the prohibited communication terminals.
Here, the position relation data may indicate a direction of each of the requesting communication terminals from the radio communication permission control apparatus. In this case, in the (d) determining step, it may be determined whether or not a direction of the requesting communication terminal indicated by the estimated position relation data is in a predetermined directional range corresponding to any of the position relation data stored in the storage section.
Also, the position relation data may indicate an incoming angle of the communication start request signal transmitted from each of the requesting communication terminals to the radio communication permission control apparatus. In this case, in the (d) determining step, it may be determined whether or not an incoming angle of the communication start request signal from the requesting communication terminal indicated by the estimated position relation data is in a predetermined angle range corresponding to any of the position relation data stored in the storage section.
Also, each of the requesting communication terminals may transmit position data of the requesting communication terminal together with the communication start request signal. In this case, in the (c) estimating step, the position data as the position relation data may be extracted. Also, the position relation data may be the position data indicating a position of each of the requesting communication terminals. In this case, in the (d) determining step, it may be determined whether or not a position of the requesting communication terminal falls within a predetermined position range corresponding to any of the position relation data stored in the storage section.
Also, the position relation data may be held in the storage section for a predetermined time period.
Also, the predetermined time period may be a time period during which the requesting communication terminal is regarded not to move farther than a predetermined distance.